1. Field of the Invention
The present invention relates to an automatic bread producing machine which automatically produces bread once the given ingredients are set in the machine.
2. Description of the Prior Art
The conventional bread producing machine of this type has, in general, a structure like one shown in FIG. 24. In FIG. 24, numeral 1 denotes a chassis mounted at a bottom of a lower case 3. An upper case 2 is mounted onto the lower case 3 so as to cooperatively form a body of the bread producing machine. In the machine body, a baking chamber 4 is formed above the chassis 1. The baking chamber 4 accommodates therein a bread vessel 6 in which the given ingredients of bread are set. The bread vessel 6 is formed of die-cast aluminum. An essentially cylindrical bread vessel support 8 is provided at a bottom of the bread vessel 6.
As shown in FIG. 25, the bread vessel support 8 has fixed ribs 7 integrally formed on the lower circumference thereof for preventing rotation of the bread vessel support 8 and thus the bread vessel 6. Specifically, at a bottom of the baking chamber 4 is fixedly provided a vessel mounting support 10 of an essentially cylindrical shape which receives therein the bread vessel support 8. The vessel mounting support 10 has, on its inner circumferential wall, protruding portions 10a upon which the fixed ribs 7 of the bread vessel support 8 are arranged to abut so as to prevent rotation of the bread vessel 6 relative to the vessel mounting support 10. The bread vessel 6 has a hub opening at a center of its bottom for receiving therethrough a rotation shaft 9a. The rotation shaft 9a has one end inside the bread vessel 6 at the bottom thereof, onto which a mixing vane 9 is detachably mounted for mixing the bread ingredients put in the bread vessel 6. The rotation shaft 9a has the other end outside the bread vessel 6, onto which a driven-side connector 9b is mounted. The driven-side connector 9b engages with a driving-side connector 38b mounted onto a rotation shaft 38a of a pulley 38 which is connected to an output shaft of a motor 5 via a belt 20. Accordingly, a torque of the motor 5 is transmitted to the mixing vane 9 via the pulley 38, the driving-side connector 38b and the driven-side connector 9b. FIGS. 26A and 26B are perspective views for showing the driven-side and driving-side connectors 9b and 38b, respectively.
In the foregoing structure, when a load applied to the mixing vane 9 is increased, the driven-side connector 9b tends to run over projections, each having a triangular cross-section, of the driving-side connector 38b so that the bread vessel 6 tends to move upward. In order to prevent this upward movement of the bread vessel 6 so as to ensure the normal stable engagement between the driven-side and driving-side connectors 9b and 38b, fixing springs 11 are provided to firmly press the bread vessel 6 at an upper end thereof as shown in FIG. 27. In FIG. 27, each of the fixing springs 11 is formed of an elastic steel wire and includes a step 11a for receiving the upper end of the bread vessel 6. The fixing spring 11 has one end fixed to an inner surface of a surrounding wall of the baking chamber 4 by means of a proper mounting fixture 12, such as a screw. The fixing spring 11 has the other end protruding outward through an opening 4a formed at the surrounding wall of the baking chamber 4. Accordingly, when mounting the bread vessel 6 in the baking chamber 4, each of the fixing springs 11 first abuts against the outer periphery of the bread vessel 6 so as to deflect in a direction A. When the bread vessel 6 is placed in position, each fixing spring 11 is restored so as to receive the upper end of the bread vessel 6 at the step 11a.
Referring back to FIG. 24, a heater 14 is arranged in the baking chamber 4 for heating the bread vessel 6. A temperature sensor 15 is further arranged in the baking chamber 4 for monitoring a temperature of the bread vessel 6. Numeral 16 denotes an outer lid with an inner lid 17 for opening and closing the baking chamber 4 relative to the exterior. Numeral 18 denotes an operation panel for a user to manually set a baking time, start cooking and the like. The operation panel 18 includes a control unit for controlling energization of the motor 5 and the heater 14 based on temperature data monitored by the temperature sensor 15, time data and others so as to automatically execute processes of mixing, aging, fermenting and baking. Numeral 19 denotes a capacitor for driving the motor 5.
FIG. 28 shows another example of the conventional bread producing machine, wherein a battery, such as a coin-shaped lithium battery, is provided for backup protection of a microcomputer and maintaining a function of a clock. In FIG. 28, the same or like components are represented by the same reference numerals as those in FIG. 24.
In FIG. 28, a chassis 1 firmly holds a plate-metal body 22 of the machine at its lower end in cooperation with a bottom plate 21 in a sandwiched manner. In the machine body 22, a baking chamber 4 having a heater 14 therein is formed above the chassis 1. The baking chamber 4 accommodates therein a bread vessel 6 in which the given ingredients of bread are set. The bread vessel 6 is detachably mounted onto a vessel mounting support 10 in a sandwiched manner. A rotation shaft having an upper end mounted with a mixing vane 9 and a lower end mounted with a driven-side connector 24 is rotatably supported at the center of the bottom of the bread vessel 6. The driven-side connector 24 engages with a driving-side connector 26b mounted onto an upper end of a rotation shaft 26a which is rotatably supported by the vessel mounting support 10. The shaft 26a has a lower end mounted with a large pulley 27 which, in turn, is connected to a small pulley 28 via a belt 20. The small pulley 28 is mounted onto an output shaft of a motor 5 which is fixed to an underside of the chassis 1. Accordingly, the mixing vane 9 is rotated by the driving torque from the motor 5. Numeral 23 denotes a lid for opening and closing the baking chamber 4 relative to the exterior.
A power supply board 29 is an electric drive circuit board for supplying power to the heater 14 and the motor 5 and fixed on the chassis 1 via a board base 30 formed of resin. A microcomputer board 31 is an electric circuit board for outputting control commands to electronic elements, such as a triac and a relay, which perform switching operations for the heater 14 and the motor 5. The microcomputer board 31 is connected to the power supply board 29 via a cable 32 and held in a receiving section 33 provided in a cover 34 of the machine. Further, the microcomputer board 31 is provided with a crystal oscillator and a liquid-crystal display for showing time and an ongoing cooking process. Numeral 35 denotes a battery board in the form of a paper phenol laminate having a coin-shaped lithium battery fixed thereon. The battery board 35 is connected to the microcomputer board 31 via leads 36 and held by a holder 37 which is fixed to the cover 34 by means of a screw. The screw is inserted through an opening formed at the cover 34.
When the machine starts to be operated with the bread ingredients put in the bread vessel 6, the microcomputer board 31 controls the operations of the heater 14 and the motor 5 so that the machine executes, in order, processes of mixing, aging and fermenting of bread dough, and then heats the inside of the baking chamber 4 up to a high temperature of 150.degree. C..about.230.degree. C. for baking bread. The microcomputer board 31 is normally operated with power which is supplied via the plug-socket connection. On the other hand, when the plug is disconnected from the socket, power is supplied to the microcomputer board 31 from the battery board 35 for maintaining the stored data and the clock function.
In the former bread producing machine, however, in order to stably hold the bread vessel 6 in the baking chamber 4, no play is substantially provided between the bread vessel 6 and each fixing spring 11, and the pressing force of each fixing spring 11 is set to be large. This makes it difficult to set the bread vessel 6 in position against the pressing force of the fixing springs 11, and further makes it difficult to detach the bread vessel 6 from within the baking chamber 4. Accordingly, for example, such problems are likely to occur that, when mounting the bread vessel 6 with the given bread ingredients put therein, the bread ingredients spill over the bread vessel 6 due to an extreme force being applied to the bread vessel 6, and that the machine is operated while the bread vessel 6 is not properly positioned in the baking chamber 4. As a result, the bread is not well baked to waste the bread ingredients, and portions of the machine are subjected to damages due to, for example, thermal deformation. Further, for locking the bread vessel 6 relative to the vessel mounting support 10, the fixing springs 11 and the mounting fixtures 12, such as the screws, are additionally required, with the openings 4a further required at the surrounding walls of the baking chamber 4 for allowing the corresponding ends of the fixing springs 11 to pass therethrough. This increases the number of the parts of the machine and the number of the assembling processes of the machine, leading to the increased cost of the machine.
On the other hand, it is necessary to provide certain gap or play in the connection between the bread vessel support 8 and the vessel mounting support 10 for easily mounting and detaching the bread vessel 6 onto and from the vessel mounting support 10. Thus, while the mixing vane 9 is rotated and performs the mixing process to prepare the bread dough, every time the bread dough in the bread vessel 6 rolls and hits an inner wall surface of the bread vessel 6, the bread vessel support 8 along with the bread vessel 6 moves relative to the vessel mounting support 10 so that corresponding sounds are generated between the bread vessel support 8 and the vessel mounting support 10, and further creaking sounds are generated between the fixing springs 11 and the corresponding walls of the baking chamber 4. These sounds in operation are very noisy.
Further, the optimum mixing degrees of the bread dough differ depending on kinds of bread and ingredients. However, since a mixing strength provided by the mixing vane 9 can not be adjusted, the mixing degree can only be adjusted by adjusting a mixing time. This makes it difficult to achieve the optimum mixing process, and further, inevitably changes a cooking time.
Moreover, in the latter bread producing machine, when changing the battery, it is necessary that the battery board 35 be replaced entirely. This lacks handiness and leads to a high cost for changing the battery. Further, when a liquid, such as water, invades the cover 34 through the opening for mounting the holder 37, the battery board 35 is subjected to a leak due to the invaded water, thereby unable to provide the backup protection for the microcomputer and maintain the clock function.